Gas blast circuit breaker



March 1l, 1947.

H. THOMMEN ETAL GAS BLAST CIRCUIT BREAKER Filed Feb. `18. 1944 '//ll/llllllll Patented Mar. 11, 1947 GAS BLAST CIRCUIT BREAKER Hans Thommen and Alfred Halm, Baden, Switzerland, assignors to Aktiengesellschaft Brown, Boveri & Cie., Baden, Switzerland, a jointstock company Application February 18, 1944, Serial No. 522,935 In Switzerland February 18, 1943 2 Claims.

The present invention concerns gas blast circuit breakers with one or moreA points of interruption which are located in switch chambers having discharge openings for the gas, these openings being capable of being closed by means of valves. The object of closing the discharge openings of the switch chambers is to enable the contacts of the points of interruption to be kept open when pressure gas is present, so that the danger of voltage hash-overs is reduced and a saving in pressure gas is achieved.

With the known circuit breakers of this type the closing valve for the discharge openings in the switch chamber follows the switching movement of the moving switch contact in such a manner that when the latter moves into the open position the valve is closed against the action of a spring and when the contacts are closed the valve is opened by this spring. It is also known to close and open the valve mechanically, electrically or pneumatically by means of pressure gas taken from the storage container which supplies the blast air for the extinction of the arc. These arrangements, however, not only require reversible mechanisms with complicated rodding and piping, thus necessitating constant supervision and increasing the cost of the circuit breakers, but they also increase the consumption of pressure gas and require larger storage tanks for the gas. In order to reduce the gas consumption and the size of the gas containers it has already been proposed to utilize the pressure gas which flows out of the switch chamber away from the point of interruption to actuate the valve. In this case the valve is closed by means of the pressure gas which is discharged from the switch chamber whilst the valve is opened by means of pressure gas taken from the storage container provided for extinguishing the arc, and this again necessitates the provision of pipes between the storage container and the valve.

The present invention therefore deals with a gas blast circuit breaker with one or more points of interruption of which the contacts are located in switch chambers of insulating material with metallic end elements, one of these end elements possessing openings for the discharge of the pressure gas and a valve for closing these openings, this valve being maintained in its initial position by a spring and moved out oi' this position by means of the outiiowing gas. With a circuit breaker of this kind the disadvantages referred to above are overcome and the control pipes avoided by providing in accordance with the invention on the side of the valve which is furthest away from the switch chamber a space which by means of at least one opening in the valve communicates with the switch chamber and serves to dam up the pressure gas discharged from the switch chamber, whereby the pressure gas stored in this space causes the valve to be automatically returned to its initial position.

Constructional examples of the invention are illustrated in Figs. 1-3 of the accompanying drawing where each gure shows a cross-sectional view through the Switch chamber of a gas blast circuit breaker, all elements which are not essential for an understanding of the invention having been omitted from the drawing.

The switch chamber which contains the contacts of a point of an interruption of a gas blast circuit breaker with single or multiple interruption, consists of a hollow insulator a, with metallic end parts b which allow the pressure gas to enter the switch chamber and possess discharge openings or channels e, e1 which runs substantially radially from the inside to the outside of the insulator and serve to conduct away the pressure gas from the separation point of the contacts. These discharge openings e, e1 can be closed by a valve f. At least one of the contacts c, d of a point of interruption is a hollow contact. In the constructional examples illustrated the moveable pin contact d co-operates with the stationary hollow contact c. The contacts c, d are arranged centrally on both sides of the metallic element b in such a manner that together they form a constructional unit, these units being capable of multiplication when they have to serve as the points of interruption for a circuit breaker with multipie interruption and having switch chambers arranged in series. At the metallic parts b which form the floor piece or cover for the switch chamber of a circuit breaker with a single point of interruption or for the switch chambers at the beginning and end of a circuit breaker with multiple interruption, the superiiuous contact element can be omitted.

With the constructional example shown in Fig. l the valve consists of a circular disc f which by means oi the spring g is held in its initial position where it keeps the discharge channel e and discharge opening e1 for the pressure gas closed. The valve is opened by the pressure gas, which after it has opened the contacts c, d and subjected the arc formed between these contacts to a gas blast, discharges through the channel e. The pressure of the discharging gas then exceeds the pressure of the spring g and the valve reaches its open position which is limited by the stop h.

gamers in the open position valve f shuts ofi' an air storage space z' which by means of a central opening 7c in the valve disc is in communication with the discharge channel e and is filled by the gas discharging from the switch chamber. The volume of the space z' determines the time required for the valve to reverse itsl direction of motion due to the eect or the pressure of the gas stored in the space i, whereby the valve is returned to its initial position where it closes the discharge channel e. The return of the valve f is achieved at the beginning of the return movement by the pressure difference resulting from the difference between the cross-sectional area of the discharge channel e and the area of the opening of the storage space z determined by the limiting edge h, this difference in areas being supported by the spring g. Duringthis time the pressure in the switch chamber a remains substantially unchanged. Valve f is thus moved from its initial position to its end position by the gas discharging ,from the switch chamber and after a certain time has lapsed it is moved back again into its initial position, this cycle of operation then repeating itself. The time required for this operation can be selected as desired and is fixed by the volume of the storage space z' which thus acts as a time element. It is expedient to provide protective Awalls m on the face of the valvey in order to protect the sliding surface of the valve against deposits from the gas discharged from the switch chamber. The switch chamber can possess one or more discharge openings which are distributed along its periphery and are provided with separate valves.

With the constructional example shown in Fig. 2 the valve is a ring valve f1 with at least one bore 7c whose surface lies perpendicular to the axis of the switch chamber a containing the contacts c, d. The method of operation is the same as with the arrangement shown in Fig. 1. The opening 7c can be omitted if the annular valve disc has sufcient clearance;

A modified form of the invention is illustrated in Fig. 3 where the valve consists of a springloaded open ring with overlapping edges. The effective surface of the annular disc lies parallel to the axis of the switch chamber a. containing the switch contacts. With this arrangement the valve is also openedby the spring ring being expanded by the gas discharging from, the switch chamber, and then after a certain time, which is determined by the volume of the storage space i, the valve is closed again by the pressure which acts on the other side of the ring and causes it to return to its original position.

By employing the gas discharged from the switch chamber to produce the successive movements of the valve as described above, not onl7 is pressure gas economised but the discharge openings and switch chambers are also protected against the entry of foreign matter such as dust, snow, etc. Circuit breakers of this kind are, on account of the automatic return of the valve into the initial closed position, particularly suitable for reclosing when clearing short circuits on lines which have to be protected against disturbances.

The valve shown in Fig. 1 is of course not restricted to the circular shape shown; any other suitable shape can be chosen.

We claim:

1. A gas blast circuit breaker comprising a tubular switch chamber formed of insulating material, a metallic end closure for said switch chamber, a hollow contact on said end closure, said end closure being provided with an internal conduit for carrying pressure gas admitted thereto through said hollow contact, said conduit being provided with an exhaust port opening to the atmosphere, a movable contact in said switch chamber adapted to engage said hollow contact and normally biased into engagement with said hollow contact, said movable contact being adapted to be disengaged from said hollow contact by pressure gas entering said switch chamber and a valve for closing the exhaust port of said conduit, said valve comprising a member normally biased to an exhaust port closing position and adapted to be opened by the ow of pressure gas from said chamber into said conduit, a housing in which said member is adapted to reciprocate and cooperating therewith in the open position thereof to provide a pressure gas storage space, said member being provided with a bleed port communieating with said gas storage space, whereby the gas pressures acting on said member will be gradually equalized by the pressure gas filling said storage space so that the normal biasing of said member will act to close said valve.

2. A device as claimed in claim 1 in which said member oi said valve is provided with a blast deflecting skirt whereby the gas blast is prevented from depositing foreign material on the housingr wall and obstructing the movement of said member.

HANS THOMMEN. ALFRED HALM.

REFERENCES CITED The .following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,221,720 Prince Nov. 12, 1940 2,345,724 Baker et al Apr. 4, 1944 2,018,136 Lange Oct. 22, 1935 2,196,247 Browne Apr. 9, 1940 2,197,148 Hasbrouck Apr. 16, 1940 2,279,536 Thommen Apr. 14, 1942 

